The mosquito-borne virus causes symptoms similar to dengue and chikungunya, including fever and joint pain. According to the U.S. Centers for Disease Control, no confirmed cases of Zika have led to death, and symptoms normally last no longer than a week.

However, in recent weeks health officials have raised concerns the virus could be linked to a rare brain defect among newborn babies, which has caused deaths.

WATCH: The Zika Virus Spreads Around Latin America

“Although Zika typically causes only mild symptoms, outbreaks in Brazil have coincided with a marked increase in microcephaly—or unusually small head size—in newborns,” PAHO said. “Pregnant women should be especially careful to avoid mosquito bites.”

In Brazil, microcephaly, a condition which affects the development of an infant’s brain, is believed to have affected 3,893 newborn babies since authorities began investigating the surge in October, local officials announced earlier this month.